Art of devulcanizing rubber.



psi sans PATENT oniuoa.

HENRY J. MAYERS, OF CLEVELAND, OHIO, ASSIGNOR TO THE EMPIRE RUBBERCOMPANY, A CORPORATION OF OHIO.

ART OF DEVULCANIZING RUBBER.

No Drawing. Continuation of application Serial No. 664,333, filedDecember 7,1911.

filed February 17, 1912. Serial No. 678,219.

T 0 all whom it may concern Be it known that I, HENRY J. MAYERS, acitizen of the United States, and a resident of Cleveland, Cuyahogacounty, and State of Ohio, have invented new and useful Improvements inthe Art of Devulcanizing Rubber, of which the following is aspecification.

This application is filed as a continuation of application Serial No.664,333, filed December 7, 1911, for the same subject matter.

In an application filed under date of December 7 1911, by Samuel E.Allen, Serial No. 664,372, is described an invention which consists in anew and improved process for devulcanizing rubber producing a new andimproved product as well as the elimination of fibrous material, if anybe present; said invention involving two discoveries; (1) that a certainkind of oil has the capability of devulcanizing rubber, and (2) thediscovery that this may be availed of on vulcanized goods containingfiber with the action of a fiber destroying agent; preferably concurrentin a single operation.

The present invention involves the further discovery that the qualitiesof the product may be improved by the modifications in the processhereinafter described.

In order to make my description complete I will describe the wholeprocess inclusive 0 my modifications.

The oil employed in my process is a distillate of pine wood having aspecific gravity between that of oil of turpentine and that of resinoil. In other words, between about .88 and .96 at 15 C. Morespecifically, the oil that I have employed is about from .93 to .95specific gravity and may be obtained as a distillate from the stumps oflong leaf pine trees (Pinus palustm's) by distilling according to thewell known resin or other bath process wherein the liquid of the bathhas a boiling point above that of the oil and subsequent redistillation.This oil is to be found on the market and maybe further identified bythe fact that the greater part of its bulk in a dry still will distilover at a tem erature of between 200 and 220 C. The pre erable specificgravity is from .935 to .945 at 15 C. I subject such oil to a refiningdistillation the effect of which is to eliminate the resinousconstituents, such as rosin, pitch and tar and the product of whichrefining Patented J an. 4, 1916.

distillation therefore may be designated as deresinated oil of pine. Igive the following examples of this refining distillation process.

Example 1 started with a commercial oil of the kind above referred tohaving a specific gravity of about .945land an optical rotation of aboutminus 3 54. This startmg ml is subjected to steam distillation either bythe passage of steam or by the heatmg of the oil in the presence ofwater until the distillate begins to grow dark. The temperature of thedistilling vapors is with trifling variations about 212 F. The productof this distillation showed a specific gravity of .943 and an opticalrotation of minus 3 15.

Example 2 started with an oil of the same speclfic gravity and rotationand the distillatlon was conducted under the same conditions exceptingthat salt (sodium chlorid) was added in the proportion of 165 grams ofsalt to 2500 cc. of oil and 3000 cc. of Water.

The product of this example showed a specific gravity of .943 and anoptical rotation of minus 3 15.

Example 3 started with oil of the same speclfic gravity and opticalrotation and the distillation was conducted under the same conditions asin the second example except ing that to the oil, water and salt wasadded amyl acetate in the proportion of 25 cc. The product of thisexample showed a specific gravity of .942 and an optical rotation ofminus 3 15.

Example 4 started with similar oil having a specific gravity of .943 andan optical rotation of minus 4 24 and resulted in a finished oil producthaving a specific gravity of .940 and an optical rotation of minus 4 0.This 4th example of the process was carried on as follows: 54 pounds ofordinary salt (sodium chlorid) were dissolved in 41 gallons of water, towhich solution were added 800 pounds of said oil; 20 pounds of eu-;,c'alyptus globulus, 20 pounds of oil of citronella and 8 pounds ofamylacetate. The mass was distilled slowly in a copper still of about300 gallons capacity heated by steam coils containing steam at about 40pounds pressure. A thermometer placed in the vapor at-the top ofthestill showed about 212 F. This distillation occupied about 30 hours. Ihave also found in the production of the oil set forth in this example(4) that the salt This application and amylacetate may be omitted, andequally good results obtained by such oil in the process ofdevulcani'zation.

In each of the above examples, the product was dried by decantation andthe prod not of each example forms a slightly turbid solution in equalvolumes of grain alcohol at ordinary temperature.

In devulcanizing rubber containing no fiber, known in the trade as puregum stock, I proceed as follows: The rubber is ground so as to passthrough a 3 to 5 mesh screen and placed in the mixing tank. Water isadded to just submerge the rubber. The said oil is distributed over thesurface and mixed either by hand or machinery. The proportions are aboutas follows: 200 lbs. pure gum stock, 600 lbs. water, 17 lbs. said oil.

The mass is dumped into a closed devulcanizing tank which is run into adevulcanizing oven Where it is inclosed so as to maintain pressure andwhere it is allowed to remain for about 15 hours at a temperature and'pressure corresponding with about 100 lbs. steam pressure (327 F.)applied either by .admitting the steam into a surrounding steam jacketor directly into the devulcanizing oven. The mass is then removed fromthe tank and batched ina washer and dried.

In devulcanizing rubber containing cotton fiber such as old automobiletires, I proceed as follows: The rubber is ground so as to pass througha 3 to 5 mesh screen and placed in a closed mixing tank. .a solution ofsulfuric acid in proportions as below is added. The said oil isdistributed over the surface and mixed by machinery or hand. Theremainder of the process is the same as with the pure gum stock. Theproportions are as follows: 200 lbs. ground tires, 800 lbs. water, 2gallons sulfuric acid, 3 gallons saidoil.

In devulcanizing'rubber containing more or less wool fiber mixed withthe cotton, such as old rubber boots and shoes, I proceed as follows:The rubber is ground so as to pass through a 3 to 5 mesh screen andplaced in a closed mixing tank submerged with a 2% solution of sulfuricacid and allowed to stand for 12 hours at ordinary temperature. The saidoil is then distributed over the surface, and mixed. Then more sulfuricacid is added. The remainder of the process is as before. Theproportions are as follows: 200 lbs. ground boots and shoes, 600 lbs.water acidulated with 2% sulfuric acid, 2 gallons sulfuric acid, 3gallons said oil.

Instead of a devulcanizing tank in a stationary devulcanizer, a doublejacketed revolving devulcanizer may be employed withthe heat andpressure above specified.

I prefer to apply the heat by passing a current of steam of about 100lbs. pressure through the closed devulcanizing oven so that said steamcirculates not only in contact with the cover over the mass beingtreated, but also in contact with the sides and bottom of the metal tankcontaining the mass and thereby applying the heat to the mass from everydirection. The cover of the devulcanizing tank that I prefer to employis a loose cover not necessarily excluding the steam.

I do not limit myself to sulfuric acid as the fiber removing agent,equivalents being possible. Excepting when expressly specified inparticular claims, I do not limit myself to oil containing the otheringredients added in the refining process nor to the oil of long leafvariety of pine, nor to the more particular specific gravities mentionednor to the oil obtained by the rosin bath process.

The product of devulcanized rubber produced as above set forth, Ibelieve to differ from any product heretofore obtained in that itpossesses superior efficiency for coating cloth known in the trade asfrictioning and for any other purposes requiring freedom fromrefractoriness in working or requiring plasticity or ease of flow, andat the same time lending itself to the production of an efficientvulcanized product of high tensile strength. The explanation for thesesuperior qualities of the product I am at the present time unable tofurnish but believe them to be attributable to the superiordevulcanization by my process.

I believe that the efficiency of the above described refining process inits efiect upon the, qualities of the product is largely due to the factthat it removes from the oil resin, pitch, tar and turpentine and that,therefore, the oil applied to the rubber may be said to be de-resinatedand de-turpentinated, and I do not wish to be understood as limitingmyself to the kind of refining process by which this is accomplished. Ialso believe that the presence of the oil of eucalyptus has a beneficialeffect upon the action of the other oil in its effect upon thedevulcanized rubber product.

What I claim and desire to secure by Letters Patent of the United Statesis:

1. The process of devulcanizing rubber which consists in subjecting thesame to a bath containing de-resinated oil of pine.

2. The process of devulcanizing rubber which consists in subjecting thesame to a bath containing a de-resinated and de-turpentinated'oil ofpine.

.3. The process of devulcanizing rubber which consists in subjectingthesame to a bath containing a de-turpentinated oil of me. Y

4. The process of devulcanizing rubber which consists in subjecting thesame to a .bath obtained by the distillation of pine wood between .88and .96 specific gravity and subsequently refined by distilling at atemperature of about 212 F. with water.

5; The process of devulcanizing rubber which consists in subjecting thesame to a bath containing oil obtained by distilling pine wood at aspecific gravity of between .88 and .96 and subsequently refined bydistillin in conjunction ,with a salt.

6. The process of devulcanizing rubber which consists in subjecting thesame to a bath containing oil obtained by distilling pine wood at aspecific gravity of between .88 and .96 and subsequently refined bydistilling in conjunction with oil of eucalyptus.

7. The process of devulcanizing rubber which consists in subjecting thesame to a bath containing oil obtained by distilling.

pine wood at a specific gravity of between .88 and .96 and subsequentlyrefined by distilling in conjunction with oil of citronella.

8. The process of devulcanizing rubber which consists in subjecting thesame to a bath containing oil obtained by distilling pine wood at aspecific gravity of between .88 and .96 and subsequently refined bydistilling in conjunction with a salt and oil of eucalyptus.

9. The process of devulcanizing rubber which consists in subjecting thesame to a bath containing oil obtained by distilling pine wood at aspecific gravity of between .88 and .96 and subsequently refined bydistilling in conjunction with a salt and oil of citronella.

10. The process of devulcanizing rubber which consists in subjecting thesame to a bath containing oil obtained by distilling pine wood at aspecific gravity of between .88 and .96 and subsequently refined bydistilling in conjunction with a salt, oil of eucalyptus and oil ofcitronella.

11. The process of devulcanizing rubber which consists in subjecting thesame to a bath containing oil obtained by distilling pine wood at aspecific gravity of between .88 and .96 and subsequently refined Mydistilling in conjunction with amylacetate.

. 12. The process of devulcanizing rubber which consists in subjectingthe same to a bath containing oil obtained by distilling pine wood at aspecific gravity of between .88 and .96 and subsequently refined bydistilling in conjunction with a salt and amylacetate.

13. The process of devulcanizing rubber which consists in subjecting thesame to a bath containing oil obtained by distilling pine wood at aspecific gravity of between .88 and .96 and subsequently refined bydistilling in conjunction with a salt, oil of eu calyptus, oil ofcitronella and amylacetate.

In testimony whereof, I have hereunto signed my name in the presence oftwo subscribing witnesses.

HENRY J. MAYERS.

Witnesses: I

C. W. EHRHE, R. F. VALENTINE.

